Automatic film cleaner



R. GRUNWALD ET AL 3,019,464

Feb. 6, 1962 AUTOMATIC FILM CLEANER Filed Aug. 18, 1958 2 Sheets-Sheet 1 bmw Feb. 6, 1962 R. GRUNWALD ETAL AUTOMATIC FILM CLEANER 2 Sheets-Sheet 2 Filed Aug. 18, 1958 JF-ez/er-dbrs fiber? Gram/law flashcard 5 Ma acs ward fi U181? l lo 3,019,464 AUTOMATIC FILM CLEANER Robert Grunwald, Northbrook, Richard R. Wallace,

Wilmette, and Howard Bowen, Evanston, ill, assignors to The Harwald Company, Inc., Evanston, Ill., a corporation of Illinois Filed Aug. 18, 1958, Ser. No. 755,693 7 Claims. (Cl. -100) Our invention relates to an improved automatic film cleaner particularly useful with an automatic film inspecting device of the type shown in Robert Grunwald Patent 2,699,676 and in the co-pending application of Robert Grunwald and Richard R. Wallace, Serial Number 591,962, filed June 18, 1956, entitled Control Mechanism for Automatic Film Inspecting Device, now Patent No. 2,939,972.

In accordance with the present invention a lengthy motion picture film is cleaned by drawing the same between a pair of moving cleaner tapes. These cleaner tapes sandwich the film being cleaned and are guided to the sandwiching position by a pair of conducting shoes. One shoe, preferably the lower shoe, is in fixed position. The other shoe, preferably the upper shoe, is swingable up and down to provide access to the gap between the shoes to permit the film to be inserted and removed. The movable shoe includes tape guide elements which serve to bias or force the shoe towards the closed position in response to the tension on the tape. Further in accordance with the present invention the lower shoe includes a liquid cleaner well which is controllably supplied with a conducting cleaner liquid. The amount of cleaner liquid in the gap determines the resistance measured between the two shoes. The supply of liquid cleaner fed to the gap is interrupted when the resistance falls below a predetermined value.

In use, the shoes and cleaner tapes are drawn into a tight relationship with the film to wipe in constant pressure thereagainst and the liquid cleaner supply is maintained at a value giving a predetermined resistance between the shoes. This resistance is in fact a measure of the degree of extent the upper and lower tapes have absorbed the liquid cleaner. Consequently the action serves to provide a uniform degree or quantity of liquid cleaner for film cleaning purposes. Since the action that controls the amount of liquid cleaner supply is an integrating action, the mechanism operates in a self-regulating fashion to compensate for local flooding of the tape. It does not tend to give excessive liquid cleaner feed when there is an excess of liquid cleaner in one spot and an inadequate amount in another. Such flooding accordingly remains local in nature and after a period of operation the liquid cleaner spreads to cover the entire portion of the tape between the shoes due to capillary action.

It is therefore a general object of the present invention to provide an improved automatic film cleaner particularly suitable for use with an automatic film inspect ing device.

A more particular object of the present invention is to provide an improved automatic film cleaner in which the requisite amount of film liquid cleaner is automatically supplied to the film cleaning tapes.

Still another object of the present invention is to provide an improved automatic film cleaner in which the liquid cleaner is supplied to one tape and is uniformly distributed by capillary action of the tapes.

It is yet another object of the present invention to provide an improved automatic film cleaner utilizing a pair of conducting shoes between which the film cleaning tapes are sandwiched and in which an eccentrically located well on the lower shoe serves to supply liquid cleaner in controlled amounts for distribution by capillary action to both the upper and lower film cleaning tapes.

Still another object of the present invention is to provide an improved automatic film cleaner in which local flooding of the film cleaning tape does not cause loss of controlled feed.

It is yet another object of the present invention to provide. an improved automatic film cleaner having features of construction, combination and arrangement in which the unit is made particularly suitable for use with an automatic film inspecting device, is reliable in operation, has a high degree of uniform feeding of the liquid cleaner, has a mechanism which may be readily opened for inspection and adjustment while at the same time a high pressure is exerted between the shoes, and has other features particularly suitable for commercial use.

The novel features which we believe to be characteristic of our invention are set forth with particularity in the appended claims. Our invention itself, however, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference. to the following description taken in conjunction with the accompanying drawings in which:

FIGURE 1 is a side elevational view with parts broken away of an automatic film cleaner made in accordance with the present invention;

FIGURE 2 is an enlarged fragmentary cross-sectional view through axis 2Z, FIGURE 1;

FIGURE 3 is a fragmentary cross-sectional View through axis 3-3, FIGURE 1;

FIGURE 4 is a somewhat diagrammatic view showing the conducting top shoe in one position;

FIGURE 5 is a view like FEGURE 4 showing the shoe in the other position; and

FIGURE 6 is a schematic drawing of the electrical elements used in the structure of FIGURES 1-5.

There is shown generally at 10, FIGURE 1, an automatic film cleaner made in accordance with the present invention. The entire unit is mounted on rectangular panel 12 which has four edges 12a, 12b, 12c and 12d. A conducting top shoe 14 and a conducting bottom shoe 16 on the panel 12 receive velvet liquid cleaner absorbing tapes 14a and 16a respectively. The cleaning tapes move in the same direction and clean film 13 which is sandwiched therebetween and is moving in a direction opposite to that of the tapes 14a and 16a. As will be discussed in more detail hereinafter, bottom shoe 16 has a liquid cleaner well 29 which supplies the conducting cleaning liquid to the cleaner tapes 14a and 16a. The well 2%) is supplied the conducting liquid from a gravity feed bottle 22. The flow of the liquid is controlled by a solenoid valve 24 and a drip chamber 26. The solenoid valve 24 is controlled by the amount of electrical resistance between shoes 14 and 16 which varies with the amount of conducting liquid absorbed by the tapes. If the resistance falls below a predetermined value, electrical elements associated with the shoes 14 and 16 actuate the solenoid valve 24 which shuts off the supply of liquid cleaner to the system.

As best seen in FIGURE 1, film 18, which may be motion picture film which has been used and has accumulated a substantial amount of dirt and grit, is unwound from reel 30, is guided by rollers 32 and 34 along edges 12d and 12a of panel 12 into the gap separating conducting shoes 14 and 16, is cleaned therein, and then rewound on a reel (not shown). The cleaner absorbing tapes 14a and Ida are wound on reels 36 and 38 and unwound onto reels 46 and 40, respectively, all of which are mounted on panel 12. The tapes are made of velvet or other similar material which is both absorbent and friction surfaced. The tapes are wider than the film so that there is overlap beyond the film edges which enhances the distribution of the cleaning liquid to top tape 14a as will be discussed in more detail hereinafter. The reels 46 and 46 are power driven by motors or similar means (not shown). The tapes 14a and 16a move in the direction of the arrows, towards edge 12a of panel 12 whereas the film 18 travels in the opposite direction, as shown by the dotted arrow, FIGURE 1. The purpose of the opposed movement of the tapes and film is to insure that a maximum wiping effect is realized between the same to achieve maximum cleaning results. Slave reels 36 and 38 have retarding or braking devices (not shown) which exert considerable resistance to power reels 46 and 4%, respectively. The film 18 travels at a relatively fast forward pace through the gap of shoes 14 and 16 to provide maximum production of cleaned film.

Referring now to FIGURE 2, top shoe 14 and bottom shoe 16 are of stamped sheet metal of channel-shaped cross section. Cleaner tapes 14a and 16a travel across horizontal portions 14b and 16b of the shoes, respectively. The film 1 8 is sandwiched between the tapes in the manner shown. The tapes, which are of soft, resilient material, such as velvet, will compress in the center to accommodate the narrower film. There will be overlap of the tapes at either edge, however, because of the greater width of same. As can readily be seen, the liquid absorbing tapes 14a and 16a bear down against both sides of the film 18 to create a substantial friction relationship which insures good cleaning action.

As best seen in FIGURES 1 and 2, bottom shoe 16 has a liquid cleaner well 20 depending from and aflixed to horizontal portion 16b by welding or similar means (not shown). The well has an opening 20a which is cut out from horizontal portion 16b of bottom shoe 16. Tape 16a travels across the opening 20a and picks up the liquid cleaner 21 which is contained therein. It will be noted that only tape 16a travels across well 20 and consequently is the only cleaner tape that initially picks up the liquid cleaner. The top tape 14a absorbs liquid cleaner from bottom tape 16a by capillary action which takes place at the edges of the tapes that overlap. To facilitate this capillary action, the well 20 is mounted eccentrically, that is off-center, as seen in FIGURE 2. A heavy concentration of absorbed liquid cleaner at one edge of bottom tape 16a is transferred much more readily and effortlessly to the top tape 14:: than a heavy concentration in the center of the bottom tape. Thus both tapes absorb the requisite amount of liquid cleaner for efiicient and effective cleaning action.

The well 20 has a downwardly extending nipple 48 with a bore 48a leading to the well proper. Rubber or plastic tubing 50 is fitted over the nipple in air tight fashion and extends upwardly to the drip chamber 26 and is received on nipple 52 thereon as best seen in FIGURE 1. The drip chamber 26 is secured to panel 12 by bolts or otherwise (not shown) and has a glass covered opening 26a through which the rate of drip of the liquid cleaner 21 can be observed. Needle valve 28 controls the rate of liquid drip which can be varied by turning handle 2811 which extends out of edge 12b of panel 12. It will be noted that drip chamber 26 is raised with respect to well 20 so that the well is supplied liquid cleaner by gravity feed.

A feed pipe 54 connects solenoid operated valve 24a with drip chamber 26. The solenoid 24, when actuated, releases plunger 56, which is a valve stem, to open the supply of liquid cleaner from feed bottle 22. The solenoid operates intermittently and is energized by electrically operated control elements which will be described in more detail hereinafter. The solenoid 24 and its associated valve 244: are supported by elements 57 which are secured to bracket 58 by screws 60. The bracket 58 is mounted on panel 12 by welding or similar means (not shown). The feed bottle 22 is received in a spout pan 23 which fits over the portion of solenoid valve 24a projecting above edge 12b as seen in FIGURE 1.

Referring now to FIGURE 3, bottom shoe 16 is rigidly aflixed to panel 12 by welding, as shown at 17. Top shoe 14 is situated above and coextensive with the bottom shoe 16. As will be discussed in more detail hereinafter, top shoe 14 is mounted on insulating bracket 68 which is secured to panel 12 by screws 72. U-bar 44 is aflixed to the front face 14c of shoe 14' by screws 62. Legs 44a of U-bar 44 extend around the sides of shoe 14 a distance slightly greater than the width of the tape 14a.

As is best seen in FIGURES 1 and 3, tape 14a is unwound from slave reel 36, is guided around roller 42, is looped over leg 44a and is moved through the space defined by leg 44a and side face 64, is received in the shoe gap and rides along surface 14b of top shoe 14, is looped up over the leg 44a on the other side of top shoe 14 and is aflixed to power reel 46 after passing around guide roller 48. The above described threading of tape 14a creates a downward moment of force on shoe 14 when tape 14a is in motion to compress both tapes, 14a and 16a, into firm engagement with film 18.

The top shoe 14 is urged to either of two positions, that is, to engagement with bottom shoe 16 or to the upper limit of its throw defined by opening 66 in panel 12. One method of achieving this selectivity is shown somewhat diagrammatically in FIGURES 4 and 5. Tension spring 74 is aflixed at one end to bracket 76 and to detent 78 in side face 64 of top shoe 14, at its other end. Bracket 76 is so mounted that the longitudinal axis of spring 74 approaches side face 64 at an angle so that the force of the spring is exerted above the longitudinal axis of side face 64 as seen in FIGURE 4. This eccentric force creates a moment about pivot 70 which biases the side face 64 (and top shoe 14) towards bottom shoe 16.

When top shoe 14 is at the other position as shown in FIGURE 5, the force exerted by spring 74 acts below the longitudinal axis of side face 64 to create a moment about pivot 70 which biases the side face 64 (and top shoe 14) towards the upper limit of opening 66 in panel 12. The two selective positions of top shoe 14 allow the operator to change the cleaner tapes, clean the shoes and make other repairs when the top shoe 14 is in the position of FIGURE 5. Also, when top shoe 14 is in the positions of FIGURES 1-4, a minimum bias is achieved in'the absence of any cleaner tape movement.

The electrical circuitry is shown in FIGURE 6. It consists generally of the gas control tube 80 which serves to energize the solenoid or relay 82 in accordance with the resistance between shoes 14 and 16, and the solenoid valve 24 which is energized by the contacts of the relay 82. The source 84 (which may, for example, be a rectified A.-C. voltage) develops about 10 volts, a portion of which is taken ofi by the potentiometer 86. The resultant voltage is applied through resistor 88 to the control electrode 80a of the tube 80. The latter may, for example, be a 2D21 type tube. The liquid cleaner in the tapes 14a and 16a, FIGURE 2, establishes a conducting path between shoes 14 and 16, FIGURES 2 and 6, which coacts with resistance 89 to provide voltage divider action that reduces the net voltage effective on the control electrode 80a. The greater the amount of fluid between the plates 14 and 16 (and hence the lower the resistance), the lower is the voltage at the control electrode 80a.

The tube 80 is normally biased to a non-conducting state. That is, the voltage from the alternating voltage source 84 at no time causes the tube 80 to conduct. In this condition the relay 84 is not energized and the normally closed contacts 99 establish a conducting path from the A.-C. power source 92 through the solenoid valve 24 to the contacts 90, thus opening the valve and supplying cleaning fluid. Through this action, the tube 80 and the relay 82 call for fluid when there is no fluid between the plates 14 and 16.

resistance between shoes 14 and 16 is above a predetermined va1ue-that is so long as the liquid cleaner between these plates is less than a predetermined amount, When this amount is exceeded, the resistance between the plates 14 and 16 falls below a predetermined amount.- and this resistance-combined with resistances 88 and 89-defines a voltage divider that reduces the negative potential on the control electrode. 80a to a value that permits the tube 80 to conduct during a part of the A.-C. voltage cycle of source 84. The result is that current flows through the relay 82 to energize that relay, open contacts 90, and deenergize the solenoid. valve 24. The fluid supply is accordingly interrupted. Capacitor 85 limits chatter of the relay 82 when tube 80 is conducting.

It will be seen from the foregoing that the tube 80 and the relay 82 call for liquid cleaner when the resistance between plates 14 and 16 is above a predetermined value and that they bring the fluid supply to an end when that resistance is below a predetermined value.

The solenoid valve circuit has a test switch 94 which oy-passes contacts 90 to energize solenoid 24 and lamp 96 for test purposes. Test switch 94 also may be used to operate the film cleaner manually.

It is evident from the above discussion that the amount of liquid cleaner supplied to the cleaner tapes 14a and 16a is controlled by the amount of the liquid present in the shoe gap at any one time. Too little liquid in the gap causes well 20 to fill; too much liquid halts the supply. The elements that control the amount of liquid cleaner supply operate in self-regulating fashion. That is local flooding of bottom tape 16a in the vicinity of well 20 deenergizes solenoid 24 until the liquid is distributed evenly in the tapes by capillary action. At that time, the resistance increases and solenoid 24 is again energized to admit more liquid to the system. It is also evident that the force exerted by tape 14a on U-bar 44 to compress movable top shoe 14 closer to bottom shoe 16 has no relation to the control elements which influence solenoid 24 and solenoid valve 24a.

The liquid cleaner used in the present invention may be a cleaning solution using trichlorethane as a solvent to provide substantial conductivity.

A blower (not shown) is received behind a hood 100 which is mounted in panel 12 to withdraw fumes from the cleaned film. The hood is so placed that it overlays film 18 after the film has been cleaned as seen in FIG- URE 1.

While we have shown and described specific embodiments of the present invention it will, of course, be understood that alternative forms may be provided without departing from the true spirit and scope thereof. We therefore intend by the appended claims to cover all such modifications and alternative constructions falling within their true spirit and scope. What we claim as new and desire to secure by Letters Patent of the United States is:

1. An automatic film cleaner of the type in which a pair of relatively Wide liquid cleaner-absorbing tapes sandwich a relatively narrow film travelling therebetween, comprising: a top conducting shoe receiving the first tape; a bottom conducting shoe complementary to the top shoe and receiving and supporting the second tape, the bottom shoe having a liquid cleaner well with an open face across which the second tape travels; means to supply conducting liquid cleaner to said well; an electrically operated control valve operable to arrest liquid flow through said means; and control elements responsive to the electrical resistance between said shoes to actuate said control valve and to arrest the liquid flow to the well when the resistance between the shoes falls below a predetermined value.

2. An automatic film cleaner of the type in which a pair of relatively wide liquid cleaner-absorbing tapes sandwich a relatively narrow film travelling therebetween, comprising: a top conducting shoe receiving the first tape; a bottom conducting sho complementary to the top shoe and receiving and supporting the second tape, the bottom shoe having a liquid cleaner well with an open face across which the second tape travels; means to supply conducting liquid cleaner to said well; an electrically operated control valve operable to arrest liquid flow through said means; means to draw the tapes across the shoes; means responsive to the tape pull to press the shoes together; and control elements responsive to the electrical resistance between said shoes to actuate said control valve to arrest the liquid flow to the well when the resistance between the shoes falls below a predetermined value.

3. An automatic film cleaner of the type in which a pair of relatively wide liquid cleaner-absorbing tapes sandwich a relatively narrow film travelling therebetween, comprising: a movable top conducting shoe receiving the first tape; a fixed bottom conducting shoe complementary to the top shoe and receiving and supporting the second tape, the bottom shoe having a liquid cleaner well with an open face across which the second tape travels; gravity means to supply conducting liquid cleaner to said well; a solenoid valve operable to arrest liquid fiow through said gravity means; means to draw the tapes across the shoes in a direction opposite to said travelling film; means on said movable shoe responsive to tape pull to compress the shoes together; and control elements re sponsive to the electrical resistance between said shoes to actuate said control valve to arrest the liquid flow to the well when the resistance between the shoes falls below a predetermined value.

4. An automatic film cleaner of the type in which a pair of relatively wide liquid cleaner-absorbing tapes sandwich a relatively narrow film travelling therebetween, comprising: a top conducting shoe receiving the first tape; a bottom conducting shoe complementary to the top 7 shoe and receiving and supporting the second tape, the

bottom shoe having an eccentrically mounted liquid cleaner well across which the second tape travels to facilitate capillary absorption action of the first tape as it contacts the second tape; means to supply conducting liquid cleaner to said well; an electrically operated control valve operable to arrest liquid flow through said means; and control elements responsive to the electrical resistance between said shoes to actuate said control valve to arrest the liquid flow to the well when the resistance between the shoes falls below a predetermined value.

5. An automatic film cleaner of the type in which a pair of relatively wide liquid cleaner-absorbing tapes sandwich a relatively narrow film travelling therebetween, comprising: a movable top conducting shoe receiving the first tape; a bottom conducting shoe complementary to the top shoe and receiving and supporting the second tape, the bottom shoe having an eccentrically mounted liquid cleaner well across which the second tape travels; a U-bar afiixed to the top shoe and having legs extending therearound to define a space between the top shoe and said legs whereby said first tape is looped over said legs on either side of the top shoe and is received thereunder to produce a downward moment of force when the tape is in motion; means to supply conducting cleaner to said well; an electrically operated control valve operable to arrest liquid flow through said means; and control elements responsive to the electrical resistance between said shoes to actuate said control valve and to arrest the liquid flow to the well when the resistance between the shoes falls below a predetermined value.

6. In an automatic film cleaner of the type in which the film to be cleaned is sandwiched between a pair of liquid cleaner-absorbing tapes wider than said film, which tapes are moistened with a conductive liquid cleaner from a supply source, the improvement which comprises: means connected to said source to supply said cleaner to said tapes, said means including a power actuated valve to control the flow from said source to said tapes; and control means connected to said valve, said control means including a first electrode in electrical contact with the outer face of one of said tapes, a second electrode in electrical contact with the outer face of the other of said tapes, and resistance measuring means connected to said electrodes to open said valve when the electrical resistance between said electrodes is greater than a predetermined amount indicative of a dry condition of said tapes and to close said valve when the electrical resistance between said electrodes is less than a given value indicative of an excessively wet condition of said tapes.

7. An apparatus for controlling the flow of liquid to a film cleaning machine, said machine having liquid absorbent pads on which the film is wiped, said apparatus including an electrically conductive cleaning liquid; supply means to supply said liquid to said pads; and control means associated with said pads to measure the electrical resistance of a given thickness of said pads, said control means being connected to said supply means to increase the liquid flow to said pads when the electrical resistance 20 is greater than a predetermined amount indicative of dry pads and to decrease the liquid flow to said pads when the electrical resistance is less than a given value indicative of excessively wet pads.

References Cited in the file of this patent UNITED STATES PATENTS 1,162,812 Schab Dec. 7, 1915 1,273,928 Rosenfeld July 30, 1918 2,016,920 Fisher Oct. 8, 1935 2,408,438 Mills Oct. 1, 1946 2,626,620 Smith Jan. 27, 1953 2,791,788 Hausdorf May 14, 1957 2,796,618 Arndt June 25, 1957 OTHER REFERENCES Industrial Solvents, Mellan-Reinhold Publishing Corp, New York, N.Y., 1939. 

